NCCCO Articulating Crane key terms

A crane whose boom is made of two or more hinged sections that fold and unfold at hydraulic joints, allowing it to reach over and under obstructions and to stow compactly for travel.

The hinged joint between boom sections that lets the operator change the angle of an outer section independently of the main boom, altering reach, height, and capacity.

Common name for the folding outer section of an articulating crane boom, so called because the joint bends like a finger and permits close-in lifting and precise load placement.

The maximum load a crane configuration may lift under stated conditions, as published on the load chart for that boom length, radius, and outrigger setup, reduced for any attachments or nonstandard conditions.

The manufacturer-supplied table or graph giving allowable capacities for each combination of boom length, radius, boom angle, and outrigger or stabilizer condition, including notes and deductions that govern its use.

The horizontal distance from the crane's rotation center to the center of gravity of the load, measured with the boom under load and the structure deflected, not with the boom unloaded.

The turning effect of a load about the crane's tipping axis, calculated as load weight multiplied by horizontal radius, used to compare a lift against chart limits and stability margins.

The capacity boundary set by the strength of boom sections, cylinders, pins, or attachments, which governs ratings at short radii where stability is not the controlling factor.

The crane's resistance to tipping about its outrigger or wheel support line, determined by counterweight, support spread, ground bearing, and the load moment applied by the lifted load.

The line through the centers of two adjacent outrigger floats or tires about which the crane would rotate if overloaded, used when computing stability and required counterweight.

Elastic bending and joint slack that let the boom tip sag under load, increasing actual radius beyond the unloaded geometric value and reducing capacity at long reaches.

Weight that must be subtracted from chart capacity before lifting, such as the hook block, rigging, jib, basket, or attached auger, because the chart already accounts for some but not all of it.

The total weight of everything the crane supports: the load, slings and hardware, hook block, and any attached lifting device, compared against the chart value for the configuration.

Extendable hydraulic beam with a vertical float or pad that widens the crane's support base, transferring load to the ground and reducing pressure on tires and axles during lifting.

The pad or plate at the bottom of an outrigger jack that spreads force over a larger ground area, often supplemented with cribbing to reduce bearing pressure on soil or pavement.

Timber, mats, or engineered pads placed under outrigger floats to distribute load, increase bearing area, and level the crane on ground that might otherwise settle or fail.

The force per unit area that an outrigger or tire imposes on the supporting surface, which must stay below the soil or slab capacity to prevent settlement, tipping, or collapse.

The chosen location and orientation of the crane, including outrigger spread, boom stow direction, and clearance from excavations, slopes, and overhead lines, verified before lifting begins.

A documented check of the crane before each shift covering fluid levels, leaks, structural cracks, wire rope, hooks, safety devices, and outrigger function, with defects corrected before use.

Operating each crane function through its range with no load to confirm smooth motion, correct control response, and proper operation of limiters, indicators, and warning devices.

An instrument that senses boom length, angle, and pressure to compute load moment, displays radius and capacity, and warns or stops operation when the lift approaches or exceeds the rating.

A sensing system that stops hoisting or boom lowering before the hook block contacts the boom tip, preventing rope damage, block failure, and sudden load release.

Contact between the hook block and boom tip or between rope parts that can break wire rope, drop the load, or damage the boom, typically prevented by a tested anti-two-block device.

A systematic examination of crane rope for broken wires, corrosion, kinks, birdcaging, and diameter loss, with removal criteria set by the manufacturer and applicable standards.

The angle between a sling leg and the horizontal, which determines the tension in each leg; shallower angles raise leg tension and horizontal force on the load and rigging.

The maximum load a sling may carry in a given hitch and angle configuration, taken from the manufacturer's tag and reduced for wear, sharp edges, or nonvertical loading.

The way a sling attaches to the load, such as vertical, choker, basket, or bridle, each with its own capacity and load-control characteristics described on the sling tag.

A sling configuration in which the sling passes around the load and through its own eye, gripping the load as tension increases and typically reducing capacity compared with a vertical hitch.

A sling arrangement in which the sling cradles the load and both eyes attach to the hook, distributing load across two legs and often providing greater capacity than a choker.

A multi-leg sling assembly joined at a master link or ring, used to lift a load from several points while keeping legs loaded in tension and controlled.

The point where a load's weight is considered concentrated; lifting above or away from it causes tilt, shifting, and unpredictable load distribution among sling legs.

Techniques that keep a suspended load from swinging, rotating, or drifting, including tag lines, controlled hoist and swing speeds, and planning for wind and load shape.

A rope attached to a load and handled by a worker outside the fall zone to guide rotation and limit swing without the worker touching or standing under the load.

The area beneath and around a suspended load or boom where a dropped load, rigging, or boom could strike people; access is restricted to essential personnel during lifting.

A standardized arm and hand movement used by a designated signal person to direct the operator, understood by both parties and used when voice or radio communication is not practical.

A qualified individual who directs crane motion using standard signals or voice commands, positioned to see the load and operator, and authorized to stop the lift at any time.

A single emergency command, given by voice, hand, or radio, that requires the operator to halt all crane motion immediately, and which anyone on site may give.

The required distance between any part of the crane, load, or rigging and energized overhead lines, established by voltage and regulation, with barriers or de-energizing when distance cannot be kept.

A marked or barricaded area around crane operations, power lines, or swing paths that unauthorized persons must not enter, enforced for the duration of the lift.

A person who has documented training and testing on the specific crane type and meets the certification or qualification requirements applicable to the work and jurisdiction.

Rotation of the crane's upper structure about its vertical axis, which creates centrifugal force on the suspended load and must be controlled to avoid side loading the boom.

Force applied to the boom in a direction it was not designed to resist, such as dragging a load or swinging too fast, which can bend or collapse the boom structure.